Most of the methods of teaching languages take account of the factor of frequency of the lexical units of a language. In accordance with Zipf's law, the most frequent word in any language will occur approximately twice as often as the second most frequent word, three times as often as the third most frequent word, etc. In other words, a small number of words of a language that are used most frequently in the language may cover a large portion of the total number of word usages. Therefore, when learning a new language, the most effective technique is to first study these most frequent words. However, the existing methods of language learning do not take into account such a distribution of syntactic models. A study conducted on the basis of 20 million sentences stored on a server has shown that such laws exist not only in vocabulary, but also in syntax: a total of 6 million unique models were found, while 48,000 syntactic models cover 37% of the total number of sentences in texts.
A rather large number of services exist for teaching foreign languages through electronic devices, where a user needs to study rules of grammar, memorize groups of words and phrases, do exercises, and take tests. The systems of instruction in such services are not developed automatically, which proves to be a very costly and time-consuming process. Thus, it is desirable to create automated systems of teaching of syntax, grammar and vocabulary.